1. Field of the Invention
This invention relates to a work station or similar data processing system of the kind including a central processing unit (CPU). More particularly, it relates to an architecture for transferring data to and from I/O (Input/Output registers in the data processing system.
Known work stations use a specific CPU, e.g. an Intel 80386 microprocessor provided on a system board together with other chip units, such as memories, various peripheral interfaces and a system bus controller. The CPU and the above mentioned units communicate with each other, partially through buffers, over a local bus comprising control, address and data lines, all units being under tight control of the CPU through the local bus. In general, the system design is tailored for a specific CPU. This means that a large variety of different chip unit designs are required for work stations using different CPUs. The local bus also is tailored for the specific configuration. In order to maintain compatibility with other systems, detailed specifications rigidly determine the features and functions of the various units and their I/O registers. Thus, it is difficult to modify the system for expansion and improved performance.
Within the context of existing computer systems, a number of addresses are typically reserved for I/O registers. These addresses are not available for system memory and are generally limited in number. In addition to having a limited number of I/O addresses available, modern computer designs must also be compatible with software that writes multiple bytes of data to respective I/O registers at the same time.